N-(2,2,6,6-tetramethyl-4-piperidyl) substituted amidothio phosphates

ABSTRACT

0,0-Bis(aryl)amidothiophosphates, useful as light stabilizers in polyolefins, are those having the formula: ##EQU1##  wherein: R is hydrogen, alkyl of 1-12 carbons, or halogen; Ar is phenyl or naphthyl; n is 1 or 2; and R&#39; and R&#34;, which may be the same or different, are each selected from the group consisting of hydrogen, alkyl of 1-18 carbons, 2,2,6,6-tetramethyl-4-piperidyl, cycloalkyl of 5-6 carbons or both R&#39; and R&#34;, together with the N to which they are attached, form a morpholino or piperidino ring. Such compounds are made by reacting PSCl 3  with two moles of a phenol and then the product thereof with an amine.

This is a division of application Ser. No. 412,922 filed Nov. 5, 1973,now U.S. Pat. No. 3,925,518, which application was acontinuation-in-part of application Ser. No. 351,043, filed Apr. 13,1973, now U.S. Pat. No. 3,923,733.

This invention relates to stabilizing polyolefins against thedeteriorating effects of light by the use of certainO,O-bis(aryl)amidothiophosphates, alone or in combination with a2-hydroxy-4-alkoxybenzophenone, and to certain novelO,O-bis(phenyl)aminothiophosphate compounds.

As is well known, polyolefins such as polypropylene and polyethylenetend to deteriorate from the effects of light, especially ultravioletlight. This deterioration generally manifests itself as a loss oftensile strength and loss of flexibility of the polymer.

In accordance with the present invention, we have discovered thatcertain O,O-bis(aryl)amidothiophosphates, alone or in combination with a2-hydroxy-4-alkoxybenzophenone, can significantly retard or inhibit suchdeterioration.

The O,O-bis(aryl)amidothiophosphates useful for the practice of thepresent invention include those having the formula: ##EQU2## wherein: Ris hydrogen, alkyl of 1-12 carbons, or halogen; Ar is phenyl ornaphthyl; n is 1 or 2; and R' and R", which may be the same ordifferent, are each selected from the group consisting of hydrogen,alkyl of 1-18 carbons, 2,2,6,6-tetramethyl-4-piperidyl, cycloalkyl of5-6 carbons or both R' and R", together with the N to which they areattached, form a morpholino or piperidino ring. Within this class ofcompounds, those which are preferred since they give better lightstability to polyolefins are the compounds of the formula: ##SPC1##

Wherein: R is hydrogen, alkyl of 1-12 carbons, or halogen; R' and R",which may be the same or different, are each selected from the groupconsisting of hydrogen, cyclohexyl, or 2,2,6,6-tetramethyl-4-piperidyl.Especially preferred, since they give the best light stability topolyolefins, are the novel compounds of the formula: ##SPC2##

Wherein: R is alkyl of 1-6carbons or halogen; R' is cyclohexyl or2,2,6,6-tetramethyl-4-piperidyl; and R" is hydrogen or R'.

As a broad class, amidophosphates are known compounds as shown in suchreferences as U.S. Pat. Nos. 3,100,197; 3,309,317; and 3,531,550,British Pat. Nos. 941,575 and 1,039,924, and Kosolapoff"Organophosphorus Compounds" (1950) pages 278-324. Such broad class ofamidophosphates may be represented by the formula: ##EQU3## wherein: Q,Q', and Q" represent hydrogen or organic moieties, n is 1, 2, or 3, andX is oxygen or sulfur. In accordance with our invention, we havediscovered that only a very small segment of this broad class containscompounds useable alone or in combination with a2-hydroxy-4-alkoxybenzophenone to stabilize polyolefins againstdeterioration by light. The compounds of this small segment, having thestructural formulae (I). (II), or (III), supra, have certain structuralfeatures in common. First, the X of formula (IV) must be sulfur;compounds wherein the X is oxygen are greatly inferior or eveninoperative as light stabilizers in polyolefins. Second, n of formula(IV) must be one; the diamides and triamides are greatly inferior aslight stabilizers in polyolefins. Third, the Q of formula (IV) should bearomatic and the Q' and Q" should not be aromatic since compoundswherein Q is aliphatic and compounds wherein Q' or Q" is aromatic areinferior for this purpose.

The compounds of formula (IV), supra, can be prepared in several ways,one of which is described generically in U.S. Pat. No. 3,531,550(columns 3 and 4). To make the specific compounds of formulae (I), (II),or (III), supra, the appropriate phenol can be reacted withthiophosphoryl chloride in the presence of an HCl-acceptor or base togive an intermediate which can then be reacted with the appropriateamine to give the desired O,O-bis(aryl)amidothiophosphate, according tothe following reaction sequence: ##SPC3##

To make the compounds of formulae (I), (II), or (III), supra, suitablemonohydroxy-phenols include phenol, methylphenols or cresols,ethylphenols, propylphenols, butylphenols, hexylphenols, octylphenols,nonylphenols, decylphenols, dodecylphenols, dimethylphenols or xylenols,isopropylmethyl-phenol or thymol, di-tert.butylphenols, chlorophenols,methylchlorophenols, naphthols, methylnaphthols, ethylnaphthols,chloronaphthols, etc. Preferably, where the phenol has one substituent,such substituent is in the para position. Suitable amines includeammonia, methylamine, ethylamine, propylamines, butylamines,hexylamines, octylamines, dodecylamines, octadecylamines,cyclopentylamine, cyclohexylamine,4-amino-2,2,6,6-tetramethylpiperidine, morpholine, piperidine,dimethylamine, dibutylamines, dioctylamines, methylbutylamine,methylcyclohexylamine, dicyclohexylamine, etc.

The compounds of formulae (I), (II), and (III), supra, when incorporatedalone in polyolefins significantly inhibit degradation due to exposureto light. This effect can be greatly enhanced if a2-hydroxy-4-alkoxybenzophenone, a 2-(2'-hydroxyphenyl)benzotriazole, anitroxide, a tetramethylpiperidine derivative, or a3,5-ditert.butyl-4-hydroxybenzoate is also incorporated in thepolyolefin. Illustrative of such enhancing compounds are those mentionedin such prior art as U.S. Pat. Nos. 3,189,615; 3,206,431; 3,230,194;3,431,232; 3,431,233; 3,436,369; 3,448,074; 3,474,068 and 3,640,928.Such enhancing compounds include 2 -hydroxy-4-methoxybenzophenone,2-hydroxy-4-butoxybenzophenone, 2-hydroxy-4-decyloxybenzophenone,2-hydroxy-4-dodecyloxybenzophenone,2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and2,2'-dihydroxy-4-methoxybenzophenone,2-(2'-hydroxy-5'-methylphenyl)benzotriazole,2-(3'-tert.butyl-2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole,2-(3',5'-ditert.butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole,2-(2'-hydroxy-5'-tert.octylphenyl)benzotriazole,2,2,5,5-tetramethyl-4-oxoimidazolidine-1-oxide,cyclohexane-1-spiro-2'-(4'-oxoimidazolidine-1'-oxide)-5'-spiro-1"-cyclohexane,2,2,6,6-tetramethyl-4-(α-cyano-α-ethoxycarbonylmethylene)piperidine-1-oxide,1,3,8-triaza-7,7,-9,9-tetramethyl-2,4-dioxo-spiro[4,5]decane-8-oxyl,2,2,6,6-tetramethyl-4-n-butyliminopiperidine-1-oxide,benzimidazoline-2-spiro-4'-(2',2',6',6'-tetramethylpiperidine-1'-oxide),4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-(p-chlorobenzoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine,bis(2,2,6,6-tetramethyl-4-piperidyl)adipate, 2,4-ditert.butylphenyl3,5-ditert.butyl-4-hydroxybenzoate, octadecyl3,5-ditert.butyl-4-hydroxybenzoate, although2-hydroxy-4-octyloxybenzophenone, commercially available as CyasorbUV-531, is preferred and is used in the following examples as exemplaryof this class.

When used alone, or in combination with a2-hydroxy-4-alkoxybenzophenone, the O,O-bis(aryl)amidothiophosphate isusually incorporated into the polyolefin at a concentration of 0.1 to 2%by weight, preferably at a concentration of 0.2 to 0.5% on weight ofpolyolefin. When used with the enhancer, the ratio of theO,O-bis(aryl)amidothiophosphate to the 2-hydroxy-4-alkoxy-benzophenonemay be between 10/1 and 1/10, although a ratio of about 1/1 is usuallypreferred. Further enhancement is oftentimes obtained when theO,O-bis(aryl)amidothiophosphate or the combination thereof with the2-hydroxy-4-alkoxybenzophenone is used with a phosphite, such as cyclicphosphites as disclosed in U.S. Pat. No. 3,205,250, especiallydistearylpentaerythritol diphosphite; tris(p-nonylphenyl)phosphite;alkyl phosphites, such as dioctylphosphite and tridecylphosphite; alkylaryl phosphites, such as phenyl didecyl phosphite; aryl o-phenylenephosphites, such as phenyl or 4-methyl-2,6-di-t-butylphenyl o-phenylenephosphite, and the like. Other additives, such as processingantioxidants, secondary stabilizers such as dilauryl- ordistearyl-thiodipropionate, pigments, dyes, flame retardants,lubricants, etc. may also be included in the polyolefin for their usualpurposes.

For further illustration of this invention, reference should be made tothe following examples.

EXAMPLE 1 Preparation ofO,O-bis(p-tert.butylphenyl)-N-cyclohexylamidothiophosphate

To a solution of cyclohexylamine (20 grams, 0.2 mole) in 10 millilitersof dimethylformamide and 50 milliliters of benzene at 50°-60°C. wasadded dropwise, with stirring, a solution ofO,O-bis(p-tert.butylphenyl)chlorothiophosphate (20 grams, 0.05 mole) in100 millileters of benzene. The mixture was refluxed for eight hours,cooled, and filtered. The filtrate was evaporated under reducedpressure, and the oil that remained was triturated with cold methanol.The solid which formed was filtered and recrystallized twice frommethanol to give 17.6 grams of product, m.p. 107°-109°C.

EXAMPLE 2 Testing in Polypropylene

The compound of Example 1 (0.5% by weight) was dry blended with amastermix of unstabilized polypropylene (Profax 6401) and 0.2% by weightof a processing antioxidant, 2,4,6-tritert.butylphenol. The blend wasmilled for five minutes at 350°-370°F. and the milled sample wascompression molded into a film 4-5 mils thick at 400°F. The compressionmolded film, and a control film identically prepared except without thecompound of Example 1, were exposed in a Xenon Weather-O-Meter (Atlas)until they failed. The samples were considered as having failed when thecarbonyl content in the infrared spectrum reached 0.1%, a generallyaccepted point of film embrittlement. The test sample lasted 1300 hourslonger than the control, representing a life of 3.6 times that of thecontrol.

EXAMPLE 3-20

In the manner of Example 1, using the appropriate amines and appropriateO,O-bis(phenyl)chlorothiophosphates, additional compounds were preparedand tested as in Example 2. The compounds and the test results aredescribed below.

EXAMPLE 3

dicyclohexylamine reacted withO,O-bis(p-tert.butylphenyl)chlorothiophosphate to yieldO,O-bis(p-tert.butylphenyl)-N,N-dicyclohexylamidothiophosphate, m.p.208°-212°C. which, in the polypropylene test sample, lasted 800 hourslonger than the control, representing a life of 2.6 times that of thecontrol.

EXAMPLE 4

cyclohexylamine reacted with O,O-bis(p-methylphenyl)chlorothiophosphateto yield O,O-bis(p-methylphenyl)-N-cyclohexylamidothiophosphate, aliquid, which, on testing, lasted 600 hours longer than the control,representing a life of 2.5 times that of the control.

EXAMPLE 5

cyclohexylamine reacted with O,O-bis(p-chlorophenyl)chlorothiophosphateto yield O,O-bis(p-chlorophenyl)-N-cyclohexylamidothiophosphate, m.p.65°-67°C. which, on testing, lasted 900 hours longer than the control,representing a life of 3.25 times that of the control.

EXAMPLE 6

cyclohexylamine reacted withO,O-bis(p-tert.octylphenyl)chlorothiophosphate to yieldO,O-bis(p-tert.-octylphenyl)-N-cyclohexylamidothiophosphate, m.p.80°-82°C. which, on testing, lasted 400 hours longer than the control,representing a life of 1.62 times that of the control.

EXAMPLE 7

cyclohexylamine reacted withO,O-bis(2,4-di-tert.butylphenyl)chlorothiophosphate to yieldO,O-bis(2,4-di-tert.butylphenyl)-N-cyclohexylamidothiophosphate, m.p.167°-168°C. which, on testing, lasted 650 hours longer than the control,representing a life twice that of the control.

EXAMPLE 8

cyclohexylamine reacted with O,O-bis(phenyl)chlorothiophosphate to yieldO,O-bis(phenyl)-N-cyclohexylamidothiophosphate, m.p. 76°-77°C. which, ontesting, lasted 750 hours longer than the control, representing a lifeof 2.15 times that of the control.

EXAMPLE 9

cyclohexylamine reacted with O,O-bis(n-butyl)chlorothiophosphate toyield O,O-bis(n-butyl)-N-cyclohexylamidothiophosphate, a liquid, which,on testing, lasted only 300 hours longer than the control. This compoundis outside the scope of this invention.

EXAMPLE 10

cyclohexylamine reacted with O,O-bis(p-methoxyphenyl)chlorothiophosphateto yield O,O-bis(p-methoxyphenyl)-N-cyclohexylamidothiophosphate, m.p59°-61°C. which, on testing, lasted only 100 hours longer than thecontrol. This compound is outside the scope of this invention.

EXAMPLE 11

p-tolylamine reacted with O,O-bis(p-tert.butylphenyl)chlorothiophosphateto yield O,O-bis(p-tert.-butylphenyl)-N-p-tolylamidothiophosphate, m.p.199°-202°C. which, on testing, lasted 400 hours longer than the control,representing a life of only 1.5 times that of the control. This compoundis outside the scope of this invention.

EXAMPLE 12

aniline reacted with O,O-bis(p-tert.-butylphenyl)chlorothiophosphate toyield O,O-bis(p-tert.butylphenyl)-N-phenylamidothiophosphate, m.p.162-164°C. which, on testing, lasted only 150 hours longer than thecontrol. This compound is outside the scope of this invention.

EXAMPLE 13

4-amino-2,2,6,6,-tetramethylpiperidine reacted withO,O-bis(p-tert.butylphenyl)chlorothiophosphate to yieldO,O-bis(p-tert.butylphenyl)-N-(2,2,6,6-tetramethyl-4-piperidyl)amidothiophosphate,m.p. 131°-133°C. which, on testing, lasted 900 hours longer than thecontrol, representing a life of 3.25 times that of the control.

EXAMPLE 14

morpholine reacted with O,O-bis(p-tert.-butylphenyl)chlorothiophosphateto yield O,O-bis(p-tert.butylphenyl)-N-oxydiethyleneamidothiophosphate,m.p. 110°-112°C. which, on testing, lasted 650 longer than the control,representing a life twice that of the control.

EXAMPLE 15

ammonia reacted with O,O-bis(p-tert.-butylphenyl)chlorothiophosphate toyield O,O-bis(p-tert.butylphenyl)amidothiophosphate, m.p. 108°-129°C.which, on testing, lasted 700 hours longer than the control,representing a life 2.75 times that of the control.

EXAMPLE 16

di-n-butylamine reacted withO,O-bis(p-tert.butylphenyl)chlorothiophosphate to yieldO,O-bis(p-tert.butylphenyl)-N,N-di-n-butylamidothiophosphate, a liquid,which, on testing lasted 400 hours more than the control, representing alife of 1.5 times that of the control.

EXAMPLE 17

n-butylamine reacted with O,O-bis(p-tert.butylphenyl)chlorothiophosphateto yield O,O-bis(p-tert.-butylphenyl)-N-n-butylamidothiophosphate, m.p.78°-80°C. which, on testing, lasted 650 hours longer than the control,representing a life of twice that of the control.

EXAMPLE 18

tert.butylamine reacted withO,O-bis(p-tert.butylphenyl)chlorothiophosphate to yieldO,O-bis(p-tert.butylphenyl)-N-tert.butylamidothiophosphate, m.p.75°-77°C. which, on testing, lasted 550 hours longer than the control,representing a life of 1.85 times that of the control.

EXAMPLE 19

n-octylamine reacted with O,O-bis(p-tert.butylphenyl)chlorothiophosphateto yield O,O-bis(p-tert.-butylphenyl)-N-n-octylamidothiophosphate, m.p.33°-37°C. which, on testing, lasted 550 hours longer than the control,representing a life of 1.85 times that of the control.

EXAMPLE 20

cyclohexylamine reacted withO-(p-tert.-butylphenyl)dichlorothiophosphate to yieldO-(p-tert.butylphenyl)-N,N'-dicyclohexyldiamidothiophosphate, m.p.114°-116°C. which, on testing, lasted only 150 hours longer than thecontrol. This compound is outside the scope of this invention.

EXAMPLE 21

Following the procedure of Example 2, films were prepared containing0.25% of the compound of one of the foregoing examples in combinationwith 0.25% 2-hydroxy-4-octyloxybenzophenone (Cyasorb UV-531) and testedwith the results shown in the following table.

    Compound of Example                                                                             Hours to Failure                                            ______________________________________                                        1                 2200                                                        3                 3000                                                        7                 2200                                                        8                 2100                                                        14                2100                                                        17                2000                                                        19                2200                                                        ______________________________________                                    

For comparison, a control (without either additive) only lasted 500hours, and a film containing 0.5% of the2-hydroxy-4-octyloxybenzophenone without any amidothiophosphate onlylasted 1700 hours.

We claim:
 1. A compound having the formula: ##SPC4##wherein: R is alkylof 1-6 carbons, or halogen; R' is 2,2,6,6tetramethyl-4-piperidyl; and R"is hydrogen or R'.
 2. A compound as defined in claim 1 which isO,O-bis(p-tert.butylphenyl)-N-(2,2,6,6-tetramethyl-4-piperidyl)amidothiophosphate.